In general, in the method for transdermal delivery of drug, drug is difficult to penetrate stratum corneum, and so an absorptance of drug is extremely low. In particular, the larger a molecular weight of drug is, the less a drug absorptance becomes. In order to remove the aforementioned problem, the technology utilizing micro needles has been proposed. In this technology, channels penetrating a portion or all of epidermis of the skin are formed by the micro needles and drug is then delivered to the epidermis of the skin or a underlayer of the epidermis through the channels.
According to the above technology utilizing micro needles, the drug having a large molecular weight, such as insulin, hormone medicine and the like can be easily delivered. In addition, once the micro needles penetrate and stimulate the dermis of the skin, a burn or a scar can be naturally healed. Also, a generation of the collagen is induced so that it is possible to improve the skin tone and maximize an anti-aging effect.
In current, a micro needle roller is utilized as a channel forming means. The micro needle roller comprises a cylindrical roller head on which a plurality of micro needles are formed, the micro needles form a plurality of channels on the skin when the roller head is rotated. Examples of the micro needle roller are disclosed in WO02/47555, WO02/49711.
In the above conventional micro needle roller, however, the micro needles are made of stainless steel. And, the micro needles are protruded from an inside of the roller head, and so a space in which the needles can be disposed is limited. Consequently, there is a limit to a reduction of a distance between the needles.
In general, a linear distance between the needles are approximately 2 mm, it is difficult to reduce the distance between the needles to maximize the treatment effect. In addition, to utilize repeatedly the needle roller, the needle roller should be sterilized. Also, since the needle roller is made of stainless steel, its manufacturing cost and selling price become high.
As another related art, the tool for forming channel on skin for delivery drug comprising circular shaped thin plates, each of which having a plurality of skin needles formed at an end portion thereof, spacers, each of which being disposed between the thin plates, a central axis on which the thin plates and the spacers are assembled and reinforcing members mounted to both ends of the central axis is disclosed in Korean Utility Registration No. 115807.
However, the above tool has the problem that the process for manufacturing this device is complicated so that it is difficult to manufacture the device in large quantities at extremely low cost. For example, the circular shaped thin plates should be alternatively assembled, and so there is a difficulty manufacturing this tool due to the above condition. Accordingly, there are drawbacks that the above tool can not be manufactured through one shot process and a manufacturing time becomes lengthened.